1. Field of the Invention
The present invention relates to orthopedic splint type devices. Specifically, the invention relates to readily appliable and removable hyperextension limiting and stability enhancing restraining splints for the joints of digits.
2. Description of Prior Art
Several disease processes including Rheumatoid Arthritis (RA) and Osteoarthritis (OA) may adversely affect the mobility and stability of the joints of the body. Both these diseases, along with traumatic incidents that break or crush the fingers, will cause the internal forces acting upon the finger joints to become disrupted and will lead to deformities of the joints that restrict their motion or cause the joints to be unstable in one or more planes of motion. Specifically, the interphalangeal (IP) joints of the fingers of persons with arthritis will frequently become swollen and the bone structure affected in such a way that there is a loss of deliberate control of the tendons and muscles that act to move the joints through the full range of flexion and extension.
Joint instability at the proximal interphalangeal (PIP) joint and the distal interphalangeal (DIP) joint in the transverse plane results in loss of pinch prehension as the fingers deviate laterally towards the ulnar side of the hand and away from the force applied by the thumb in an attempt to achieve prehension for the performance of functional tasks. Joint instability in the sagittal plane of flexion and extension results in hyperextension, that is, extension past a neutral position of a finger, which disturbs the biomechanical forces from the tendons, ligaments and muscles that act upon the joint and results in a deformity known as the "swan-neck deformity". In this deformity, the PIP joint assumes a hyperextended position in a dorsal direction, away from the palm of the hand, and the DIP joint assumes a flexed posture, bending towards the palm, and results in a loss of extension to the neutral position.
This deformity may also persist following a traumatic injury to the finger joints that results in a fracture of one or more of the phalanges or that results in damage to the tendons, ligaments or muscles that control the finger. Most commonly, a fracture affecting the most distal phalanx, as very frequently occurs during participation in activities using a ball, and commonly known as a "baseball" or "mallet" finger, will result in a loss of extension away from the palm at the DIP joint and to instability of the joint in the sagittal plane. When uncorrected and unsupported, this deformity will often lead to a "swan-neck deformity" over time as the forces acting upon the fingers are altered in their alignment to the finger and eventually cause hyperextension and instability at the PIP joint which cannot be overcome by voluntary muscle control.
There are a variety of splints currently available to help support these unstable joints so as to impart stability to prohibit excessive and uncontrolled hyperextension or to restore range of motion to the finger joints. One variety of splints dynamically extends or flexes the joints through the forces supplied by elastic components, such as rubber bands, coiled metal springs, and spring metal wire, each having the characteristic of returning to its originally designed shape when forced into the opposite direction. The prior art splints of this variety have a drawback in that they have movable component parts and do not impart stability.
A second variety of splints, as disclosed in U.S. Pat. No. 4,270,528 issued to Hanson and U.S. Pat. Nos. 4,770,166 and 4,932,396 issued to Garris, is embodied by a ring-type structure. The ring-type structure of the Garris patent is generally made of precious metals such as gold and silver. The ring-type structure of the Hanson patent is generally made of metal such as stainless steel.
The second variety of splints, also, exhibits several drawbacks. Most importantly, these prior art splints do not provide lateral stability at the IP joints of the finger or generally correct flexion at the IP joints of the finger. Additionally, due to the narrow bands utilized to achieve the tubular ring-type design, the bands of the splints apply excessive pressure on the top of the finger, particularly in the presence of mallet finger deformities where the wearer must forcefully attempt to extend the PIP joint in order to achieve full extension at the DIP joint. Since these splints offer no adjustments in size, the bands of these splints may also constrict the finger, particularly if the finger is swollen. Another deficiency is that the splints require custom sizing and ordering through a health care professional thereby restricting access and, in many cases, being cost prohibitive. Finally, splints being embodied as metal rings may be undesirable for persons not wishing to draw attention to their deformities.
A third kind of splint is embodied in U.S. Pat. No. 3,170,460 ('460 patent) issued to Stilson. Stilson describes a splint for preventing hyperextension which constrains the finger through several points of supportive contact. The points of contact are through forward and rearward transversely disposed dorsal bridging braces and a cooperating palmar side joint seating saddle which are joined by linking components. The seating saddle is positioned beneath the center joint of the finger and the linking components are curved to maintain the geometrical relationship between the bridging braces and the seating saddle.
However, the third kind of splint, like the second variety of splints, exhibits several drawbacks. Most importantly, the splint of the '460 patent does not provide lateral stability at the IP joints of the finger or generally correct flexion at the IP joints of the finger. The splint is also deficient in that it offers no adjustments in size. As a result, the splint may either constrict the finger or migrate from the desired position on the finger.
It is therefore a goal of the present invention to overcome the problems heretofore encountered in the prior art. It is the purpose of the present invention to provide a splint that may be worn on a digit to: 1) limit hyperextension and provide lateral stability at the IP joints of a digit; or 2) correct flexion and provide lateral stability at the IP joints of a digit.
It is a further purpose of the present invention to provide a splint which contains an adjustment for size and does not require custom sizing and ordering through a health care professional. This will allow the splint to be more accessible and cost-effective than previously possible.
It is a still further purpose of the present invention to provide a splint made from materials which withstand repeated or aggressive activities so as to improve convenience and cost-effectiveness.